Catheters are increasingly used to access remote regions of the human body and, in doing so, delivering diagnostic or therapeutic agents to those sites. In particular, catheters which use the circulatory system as the pathway to these treatment sites are especially practical. Catheters are also used to access other regions of the body, e.g., genito-urinary regions, for a variety of therapeutic and diagnostic reasons. One such treatment of diseases of the circulatory system is via angioplasty (PTA). Such a procedure uses catheters having balloons on their distal tips. It is similarly common that those catheters are used to deliver a radiopaque agent to the site in question prior to the PTA procedure to view the problem prior to treatment.
Often the target which one desires to access by catheter is within a soft tissue such as the liver or the brain. These are difficult sites to reach. The catheter must be introduced through a large artery such as those found in the groin or in the neck and then be passed through ever-narrower regions of the vascular system until the catheter reaches the selected site. Often such pathways will wind back upon themselves in a multi-looped path. These catheters are difficult to design and to utilize in that they must be fairly stiff at their proximal end so to allow the pushing and manipulation of the catheter as it progresses through the body, and yet must be sufficiently flexible at the distal end to allow passage of the catheter tip through the loops and increasingly smaller blood vessels mentioned above and yet at the same time not cause significant trauma to the blood vessel or to the surrounding tissue. Further details on the problems and an early, but yet effective, way of designing a catheter for such a traversal may be found in U.S. Pat. No. 4,739,768 to Engelson. These catheters are designed to be used with a guidewire. A guidewire is simply a wire, typically of very sophisticated design, which is the “scout” for the catheter. The catheter fits over and slides along the guidewire as it passes through the vasculature. Said another way, the guidewire is used to select the proper path through the vasculature with the urging of the attending physician and the catheter slides along behind once the proper path is established.
There are other ways of causing a catheter to proceed through the human vasculature to a selected site, but a guidewire-aided catheter is considered to be both quite quick and somewhat more accurate than the other procedures. One such alternative procedure is the use of a flow-directed catheter.
This invention is an adaptable one and may be used in a variety of catheter formats. The construction technique has the benefit of producing catheter sections having small overall diameters but with exceptional strength, resistance to kinking, and recovery from kinking (even in vivo) should such kinking occur. The catheter may be used in conjunction with a guidewire, but the catheter may also be used as a flow-directed catheter with the attachment of a balloon or in combination with a specifically flexible tip.
The use of a braid or coil in a catheter body is not a novel concept. Typical background patents are discussed below. However, none of these documents have used the concept of this invention to produce a catheter having the structure and physical capabilities of the catheter of this invention.
U.S. Pat. No. 5,454,795 discloses a kink-free spiral wound catheter. The catheter includes a stiffener ribbon, typically metallic, spirally wound within the catheter body to create a catheter having controllable stiffness. The stiffener is included in a distal section of the catheter.
U.S. Pat. No. 5,702,373 shows a catheter having a reinforced braid typically of superelastic alloy ribbon located in a distal section of the catheter. The superelastic alloy ribbon provides high resistance to kinking.